One more plant with a rather complicated and controversial systematic position. According to B. Schütz’s idea of classification of Microsemineum Gymnos in the Mazanensia section, G. guanchinense, G. hossei and G. mazanense are separate taxa. However, in the works of other authors, they are widely treated as synonyms of each other. There is an opinion that Gymnocalycium guanchinense is actually an invalid name, and the proper name is Gymnocalycium hossei. At the same time, G. mazanense is said to be a synonym of G. hossei, too. On the contrary, according to K. Backeberg, G. mazanense is a good species. Moreover, Backeberg described that species himself. As for G. guanchinense, Backeberg treated it only as a form of his G. mazanense. But the seeds of the Gymnocalycium which was described by Schütz as G. guanchinense in 1947 had been offered under the name Gymn. sp. Guanchin in Frič’s seed list even earlier, in 1929, after Frič’s return from his last trip to South America.* In H. Till’s system, G. mazanense has not been granted a special place… All in all, lumpers can decide in favor of Gymnocalycium hossei, treating a number of other taxa as its subspecies or varieties. As for us, we should better just mention all available as they are. One can still find each of those three names in seed and plant lists of different providers:

Gymnocalycium hossei P 139 из коллекции Роберта Брандштеттера, Вайдхофен-на-Ибсе, Австрия. Снимки разных лет. – A plant from the collection of Robert Brandstätter, Waidhofen an der Ybbs, Austria. The pics are made in different years.

Unfortunately, this taxon varies a lot in cacti collections. Although seeds come from respectable dealers, and all of those batches are labeled as “Gymnocalycium nidulans P 138″, plants raised from them may rather look like a form of G. achirasense, or can be almost indistinguishable from G. neuhuberi.